Temperature’s rising: Heat stress

Canadian Association of Labour Media

We joke about the heat in summer months but it is really no laughing matter.

In 2001, a 44-year-old bakery worker in Barrie, Ontario, died at work of heat stress. According to the United Food and Commercial Workers, about 220 workers die every year in Canada and the U.S. from heat stress.

Excess heat is a serious workplace health and safety. Workplaces such as bakeries, food processing plants, laundry and dry cleaning establishments, and outdoor environments present a high risk.

The human body is healthy when the body’s internal temperature is around 37° C. This healthy internal temperature becomes stressed when people are exposed to higher air temperatures, when they are exposed to objects that are hot and when they are involved in physically strenuous activity. When people are exposed to two or more of these threats they are at risk of increasing their internal body temperature and suffering from heat stress.

Like other workplace health and safety hazards, the best way to reduce the risk of heat stress is to control the hazard at its source.

For example, air conditioning, effective air circulation and exhaust systems and good quality insulation on equipment like stoves and furnaces are the most effective methods for reducing or eliminating the risk.

These controls are often not what they should be. Workers should know how to protect themselves and their co-workers.

Many variables that contribute to heat stress, and individual workers and workplaces can be very different.

Passing laws based solely on exact numbers is not practical. Factors other than temperature are also significant in contribution to heat stress:

•           age – older workers are at higher risk

•           gender – women are at higher risk

•           acclimatization, the body’s ability to get used to the heat after a period of time

•           consumption of alcohol –  increases dehydration and decreases the body’s ability to control internal temperatures

•           clothing – some protective equipment retains body heat

•           air movement and humidity

•           how heavy and how fast the work is.

When there is a threat of heat stress, adequate break times and the availability of cool drinking water is required.

The humidex scale is often a guideline that workplaces use to determine certain actions. It is a measure that combines the effect of heat and humidity.

The Workplace Safety and Health Division has a scale that makes general recommendations for preventive actions when the humidex scale reaches certain levels. For example, when the humidex reads between 30 and 37, cool water should be available for workers near their workstations.

When it reaches 38–39, workers need a 15-minute break every hour. When it reaches 40–41, there should be a half hour break every hour along with the availability of cool water. If the humidex measure is up to 45, then a 45-minute break should be provided.

Humidex readings more than 45 are dangerous and work should stop.

It is important to keep in mind, however, that there are many variables, most importantly how heavy the work is. That can change these recommendations so a workplace that requires a lot of exertion will have to take preventive measures at lower humidex readings.

Employers and safety and health committees should review the particular circumstances in their workplace and assess the risks workers are exposed to.

Heat stress is a serious condition that can have serious consequences.